Impression packer

ABSTRACT

An impression packer for use in obtaining impressions in wells and having an impression sleeve formed of a mixture of natural rubber smoked sheet, silica powder and rubber processing oil.

OR iJnited States Patent Hutchison et al.

[ Dec. 24, 1974 IMPRESSION PAC KER References Cited UNITED STATESPATENTS [75] Inventors: Stanley 0. Hutchison, Bakersfield;

Glenn Anderson, Oildale; 3,046,601 Hubbert et 73/151 Gordon L. Newby,Bakersfield, all of Calif.

Assignee: Chevron Research Company, San

Primary Examiner-Donald O. Woodiel Assistant Examiner-Anthony V.Ciarlante Attorney, Agent, or Firm-Edward J. Keeling; Ralph L.-Freeland,Jr.

Francisco, Calif.

.June 25, 1973 [2]] App]. No.: 373,343

[22] Filed:

ABSTRACT An impression packer for use in obtaining impressions in wellsand having an impression sleeve formed of a mixture of natural rubbersmoked sheet, silica powder g and rubber processing oil.

50 7 wmu H12 2., M 7 W6 W mal "5 n1 0/ 3 m7 "Ur. Ha e U C d 5mm UIF 11]]2 00 555 [[i 2 Claims, 3 Drawing Figures IMPRESSION PACKER BACKGROUND OFTHE INVENTION The present invention is directed to an impression packerand more particularly this invention is directed to an impression packerutilizing a mixture of natural rubber smoked sheet, silica powder andrubber processing oil rolled into sheet form for the impressionreceiving sleeve.

It is often very desirable to know the condition of pipe or linerslocated in wells. For example, it is important to know whether or notperforations or slots in a liner are open or plugged. It is also oftenimportant to know the condition of the pipe or liner itself, i.e., is itin good condition or is it cracked or split. It is also sometimesdesirable to know what the surface of a formation penetrated by a wellis like.

One means of determining the condition of these downhole occurrences isthe use of an impression packer. An impression packer is a device whichis run down hole and has a surface which is pressed against the pipe orformation which surface will form and retain an impression ofirregularities in the surface of the pipe such as, for example,perforations or cracks in the pipe. Impression packers are not new. Suchpackers are disclosed in US. Pat. No. 2,416,441, 2,618,014; and2,653,474 for example. However, impression packers known heretofore havehad only limited success. A principal cause of the lack of success isbelieved to be the absences of a-suitable material for receiving andretaining the impression.

The present invention provides a material for forming an impressionsleeve of an impression packer. The impression, sleeve is formed of amaterial which will retain impressions and which will expand and retractso that an impression may be made and then so the packer may be removedfrom the well so the impression may be examined. The material used toform the impression sleeve must be smooth so that impression detail willbe readily observable on the sleeve after a run of the impressionpacker. That is, the surface of the impression sleeve must not be sorough that detail of the impression is lost. Generally a surface whichfeels smooth to the hand and visually appears to have no major roughnessis required.

BRIEF DESCRIPTION OF THE PRESENT INVENTION The present inventionprovides a material useful as an impression sleeve of an expandable andretractable packer which sleeve will form and retain an impression ofirregularities in a downhole surface. The material is formed of amixture of natural rubber smoked sheet, hydrated amorphous silica powderand rubber processing oil. A mixture containing from about 50 to 75percent by weight of natural rubber smoked sheet; from about to 30percent by weight of hydrated amorphous silica powder; and from about 3to percent by weight of rubber processing oil has been foundsatisfactory. A particularly desirable impression sleeve has resultedwhen the mixture comprises about 57.2 percent by weight of naturalrubber smoked sheet; about 28.4 percent silica powder; and about 14.4percent rubber processing oil.

OBJECT OF THE INVENTION A principal object'of the present invention isto provide a material for use as the impression sleeve of a packer foruse in well operations to determine the condition of a downhole surface.Further objects and advantages of the present invention will becomeapparent from the following detailed description read in light of theaccompanying drawing.

IN THE DRAWINGS FIG. 1 is an elevation view with parts broken away forclarity of presentation and illustrates apparatus assembled inaccordance with the present invention;

FIG. 2 is a sectional view taken at line 22 of FIG. 1; and

FIG. 3 is an enlarged partial elevation view and illustrates theimpression element of the present invention in' contact with a well1iner.'

DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred arrangement ofapparatus of the present invention will now be described in detail withreference to the drawings and to FIGS. 1 to 3 in particular. Theapparatus of the present invention provides an inflatable impressionpacker useful in well operations. The packer includes a tubular mandrelsection having a resilient inflatable sleeve and an impression sleeveconnected thereto. When inflated the impression sleeve expands andsealingly engages the inside of a well and conforms with irregularitiestherein. After a predetermined time period the packer is deflated andthe impression sleeve retracts. However, the impressions on the sleeveremain intact and may be investigaged when the packer is returned to thesurface.

The packer is illustrated inside of well liner 22. The liner 22 is usedto line the wall of the well as is known in the art and may contain anopening such as opening 23 which opens communication with a formationbehind the liner 22. An inflatable resilient sleeve 10 is connected atits upper and lower ends in fluid-tight relationship to an elongatedtubularmandrel section 12. The connection is made in any suitable mannersuch as by clamping units indicated by the numerals 14 and 16. Animpression sleeve 11 is connected to the resilient sleeve 10 and isexpandable and retractable therewith. The impression sleeve is adaptedto form and retain an impression record of a surface against which it ispressed.

The tubing mandrel section 12 extends through the clamping units 14 and16. The upper end of the tubing 12 is usually connected into a segmentedtubing string which extends to the top of the well. If desired, however,the tubing section may be connected through anappropriate linkage systemto a wireline. In this event suitable inflation devices for inflatingthe inflatable element are run into the well with the tubing section onthe wireline. When the tubing section is run into the well on asegmented tubing string the resilient sleeves l0 and 11 can be inflatedby flowing a fluid down the interior of the tubing string into thetubing section and then through the tubing section through suitableholes 20 and 21 therein provided.

In preferred form the lower end of the tubing section 12 is connected toa float shoe 24 by means of an intermediate sub 26. The float shoe 24has a plurality of holes 28 to permit entry of well fluids into theinterior of the shoe 24. An upwardly opening check valve, such asflapper valve 30, is located in the float shoe 24 above the holes 28.When the flapper valve is open well fluids can communicate with theinterior of the tubing section 12 and the tubing connected thereabove.

When well liquids are encountered when the inflatable packer of thepresent invention is being run into a well on a segmented tubing stringthe flapper valve 30 opens to permit entry of the well fluids into theinterior of the tubing section 12 and the tubing string. This equalizesthe pressure on the interior and the exterior of the packer and permitslater inflation of the inflatable resilient sleeves and 11 by means of arelatively small pressure differential. This is so because the pressureneeded to inflate the resilient sleeve does not need to overcome thewell pressure.

When fluid is injected into the tubing section from above to applypressure to the inflatable resilient sleeve the flapper valve is closedby the pressure and the sleeve is expanded by means of flow into theannular chamber between the tubing section 12 and the inner resilientsleeve 10. Even though a column of well liquids may extend up theinterior of the tubing and into the annular chamber 15 the packer isstill inflated by pressurizing the tubing string from the surface. Thepressure differential in the annular chamber forces the impressionsleeve to sealingly engage the well wall. When sufficient time haspassed for the impression record to be formed on the impression sleevethe pressure is released and the impression sleeve is retracted andmoves away from sealing engagement with the well wall. The retraction ofthe impression sleeve is preferably caused by the resiliency of theinflatable resilient sleeve. If desired springs or other devices may beutilized to retract the impression sleeve, for example, as taught in US.Pat. No. 2,692,446. In any event, the impression sleeve is retractedenough so that the packer may be pulled from the well without destroyingthe impressions formed thereon. After the impression packer operation iscompleted a drain port is opened below the tubing section 12 to allowthe interior of the tubing to drain as the tubing is being withdrawnfrom the well. Thus knock-off plug 32 is positioned in the adapter sub26. A sinker bar (not shown) is used to shear off the back of the plug32 to open communication from the inside of the tubing to the wellannulus.

The inner inflatable sleeve 10 of the packer is connected at its upperand lower ends in fluid-tight relationship by clamping units 14 and 16.Preferably as fully described in copending application Ser. No. 367,602filed June 6, 1973 by Stanley 0. Hutchinson, theclamping units 14 and 16disconnectably connect the flexible sleeve 10 in position over thetubing section 12. The disconnectable connection provided by theclamping units permits easy field repair or dressing" of the packer.Thus if the ends of the sleeve 10 or 11 wear or abrade near the clampingunits then one or more of the clamps is opened and the worn end or endsof the sleeve or sleeves trimmed off.

The impression sleeve is formed ofa material which will retainimpressions and will expand and retract with the expansion andretraction of the inflatable resilient sleeve. The material used to formthe impression sleeve must be smooth so that impression detail will bereadily observable on the sleeve after a run of the impression packer.That is, the surface of the impression sleeve must not be so rough thatdetail of the impression is lost. Generally a surface which feels smoothto the hand and visually appears to have no major roughness is required.In certain applications where noprolonged exposure to petroleum isexperienced, such as for example in water or gas wells, a controlledmixture of natural rubber smoked sheet and certain additives has beenfound to give good results.

The material useful as an impression sleeve in accordance with thepresent invention is a mixture of natural rubber smoked sheet, hydratedamorphous silica powder and rubber processing oil. A mixture containingfrom about 50 to percent by weight of natural rubber smoked sheet, fromabout 10 to 30 percent by weight of hydrated amorphous silica powder,and from about 3 to 15 percent by weight of rubber processing oil hasbeen found satisfactory. A particularly desirable impression sleeve hasresulted when the mixture comprises about 57.2 percent by weight ofnatural rubber smoked sheet, about 28.4 percent silica powder, and about14.4 percent rubber processing oil.

The impression sleeve material is formed by mixing the above mentionedingredients in the proper ratios. Preferably the mixing is accomplishedby first introducing a known weight of natural rubber smoked sheet intoa rubber processing rolling mill. As known in the art, a rubberprocessing rolling mill usually comprises two parallel adjustablecounterrotating rolls rotating at slightly different speeds. Rubber isfed between the rolls and the squeezing and friction caused by thedifferential speeds of the rolls heats and breaks the nerve of therubber causing it to smooth out and form a relatively thin coatingaround one of the rolls. The thickness of the sheet can be adjustedwithin limits by proper spacing of the rollers and the amount of rubberintroduced into the rolls.

After an initial period of rolling which is generally accomplished inabout 15 to 20 minutes sufficient heat and friction are generated toreduce the nerve or resiliency of the rubber to cause it to form a sheeton one of the rolls. The desired weights of the additives are then addedto the rubber as it is being rolled. To facilitate mixing the rubbersheet is continually cut off the roll and re-rolled during the mixingperiod. This results in thorough mixing and squeezing of the rubber andthe additives and eventually a smooth rubber sheet of the mixture isformed around one of the rolls. A time of about 15 to 20 minutes isgenerally sufficient to mix the rubber and the additives to form asuitable material. After a desirable sheet has been formed on one of therolls the sheet is cut and removed from the roll.

The sheet of impression material is allowed to cool. It is then ready tobe connected to an inflatable sleeve ofa packer to form an impressionsleeve in accordance with the present invention. The size of the sheet,of course, may be rolled to conform with the size of an impressionsleeve it is desired to make or the sheet taken from the rolls may be'cut into suitable strips and run through an extruder to get acontinuous sheet of desired length. For example in one demonstrationsmall rolls having a circumference of only 3 to 5 feet were used toproduce an impression material sheet. It was desired to use a continuoussheet of 30 feet in length by 16 inches in width by 0.150 inch inthickness for forming an impression sleeve. The impression materialformed on the small rolls was cut into narrow strips and run through anextruder to get a 30 foot long continuous sheet.

The so formed impression sheet is connected to an inflatable sleeve of apacker to form an impression. When using a rubber inflatable sleeve ithas been found satisfactory the bond the impression sheet to theinflatable sleeve with rubber adhesive. The preferred manner to bond thelayers together comprises coating one side of the impression sheet withrubber adhesive such as, for example, Rubatex No. 372 (a rubber adhesiveof Rubatex Corp., Bedford, Va. 24523) and allowing it to dry untilslightly tacky. During the drying period the outside of the inflatablesleeve is also coated with the rubber adhesive. The impression sheet isthen smoothly contacted with the inflatable sleeve with about a 1 inchoverlap to thus form the impression sleeve.

The natural rubber useful in accordance with the present invention isclassified as smoked sheet natural rubber. As noted at page 19 of theVanderbilt Rubber Handbook published by R. T. Vanderbilt Company, lnc.,230 Park Avenue, New York, NY. 10017 there are seven types of naturalrubber available in the market. Each type is classified according to thepreparation given the rubber and the source of the rubber. Smoked sheetis formed of coagulated rubber sheets properly dried and smoked. Thereare seven grades of smoked sheet available ranging from highest qualityNo. lXRSS to lowest quality No. 6 RSS. Although under some conditionsany of these grades may be employed in the present invention, it isusually preferred to use at least grade 1 RSS or better.

The silica powder used in accordance with the invention is hydi'atedamorphous silica. A preferred silica powder is sold under the trade nameHigh Sil 210 and is produced by Chemical Division of Pittsburgh PlateGlass Co. The function of the silica powder is to smooth out the surfaceof the rubber. Powder fills the pores of the rubber and provides asmooth surface on which impressions are clearly visible. When added tothe natural rubber in suitable proportions, i.e.,' l0 to 30 percent byweight, the silica powder provides a desirable smooth finish withoutcausing the rubber to be undesirably hard. it has been found thatnatural rubber without the addition of at least 10 percent silica powderis too rough to serve as an impression surface when detailedinvestigations are being conducted.

The liquid processing oil is useful as a plasticizer and may be one ofthe plasticizers normally used in the rubber industry. These includemineral oil and other liquid hydrocarbons and various synthetic oils.The preferred liquid processing oil for use in the present invention isa hydrocarbon based material produced by the Golden Bear Oil Company ofBakerfield, Cal, and sold under the trade and identification of LPO.

In operation the inflatable impression packer is first run into a wellto a position adjacent the surface to be investigated. Fluid is forcedinto the annular chamber to expandthe inner resilient sleeve 10 and theouter impression sleeve 11. As noted in FIG. 3 the impression 6 sleeve11 will deform into an opening such as slot 23 and a projection 34 whichis an impression of the slot will form. Generally it is desirable toapply a differential pressure in the packer of at least about psi abovethe wellbore pressure where the packer is being inflated. That is thedifferential pressure on the pressurizing fluid should be maintained atat'least 100 psi for about 10 minutes. Rarely are pressures in excess ofpsi when using the impression material of the present invention. Theimpression sleeve is useful in wells having temperatures up to about200F.

Thus in summary the present invention provides an inflatable impressionpacker for use in wells. A material is used in forming the impressionsleeve which com bines desirable qualities of resiliency and memory soas to record and retain impressions as well as to be capable ofexpansion and retraction.

Although certain preferred embodiments of the present invention havebeen herein described in order to provide an example of its constructionand steps sufficient for usage by those skilled in the art, it is to beunderstood that various changes and innovations in the structuredescribed can be effected Without departure from the basic principles ofthe invention. Changes and revisions of this sort which continue to relyon these principles are therefrom deemed to be circumscribed by thespirit and scope of the appended claims.

We claim: I

1. An impression'packer comprising a tubing section, an elongatedresilient sleeve positioned over said tubing section, means connectingthe ends of said sleeve in fluid-tight relationship with said tubingsection to form an annular chamber between said tubing section and saidsleeve, port means communicating with said annular chamber for inflatingsaid resilient sleeve and an impression sleeve connected to saidresilient sleeve for expansion and contraction therewith, saidimpression sleeve comprising a smooth rolled sheet containing between 50percent by weight and 70 percent by weight natural smoked sheet rubber,between 10 percent by weight and 30 percent by weight hydrated amorphoussilica to impart a smooth finish on said sheet and between 3 percent byweight and 15 percent by weight of rubber processing oil.

2. An impression packer comprising a tubing section, an elongatedresilient sleeve positioned over said tubing section, means connectingthe ends of said sleeve in fluid-tight relationship with said tubingsection to form an annular chamber between said tubing section and saidsleeve, port means communicating with said annular chamber for inflatingsaid resilient sleeve and an impression sleeve connected to saidresilient sleeve for expansion and contraction therewith, saidimpression sleeve comprising asmooth rolled sheet containing about 57.2percent. by weight natural smoked sheet rubber, about 28.4 percent byweight hydrated amorphous silica to impart a smooth finish on said sheetand about 14.4 percent by weight of rubber processing oil.

1. AN IMPRESSION PACKER COMPRISING A TUBING SECTION AN ELONGATEDRESILIENT SLEEVE POSITIONED OVER SAID TUBING SECTION MEANS CONNECTINGTHE ENDS OF SAID SLEEVE IN FLUID-TIGHT RELATIONSHIP WITH SAID TUBINGSECTION TO FORM AN ANNULAR CHAMBER BETWEEN SAID TUBING SECTION AND SAIDSLEEVE, PORT MEANS COMMUNICATING WITH SAID ANNULAR CHAMBER FOR INFLATINGSAID RESILIENT SLEEVE AND AN IMPRESSION SLEEVE CONNECTED TO SAIDRESILIENT SLEEVE FOR EXPANSION AND CONTRACTION THEREWITH, SAIDIMPRESSION SLEEVE COMPRISING A SMOOTH ROLLED SHEET CONTAINING BETWEEN 50PERCENT BY WEIGHT AND 70 PERCENT BY WEIGHT NATURAL SMOKED SHEET RUBBER,BETWEEN 10 PERCENT BY WEIGHT AND 30 PERCENT BY EIGHT HYDRATED AMORPHOUSSILICA TO IMPART A SMOOTH FINISH ON SAID SHEET AND BETWEEN 3 PERCENT BYWEIGHT AND 15 PERCENT BY WEIGHT OF RUBBER PROCESSING OIL.
 2. Animpression packer comprising a tubing section, an elongated resilientsleeve poSitioned over said tubing section, means connecting the ends ofsaid sleeve in fluid-tight relationship with said tubing section to forman annular chamber between said tubing section and said sleeve, portmeans communicating with said annular chamber for inflating saidresilient sleeve and an impression sleeve connected to said resilientsleeve for expansion and contraction therewith, said impression sleevecomprising a smooth rolled sheet containing about 57.2 percent by weightnatural smoked sheet rubber, about 28.4 percent by weight hydratedamorphous silica to impart a smooth finish on said sheet and about 14.4percent by weight of rubber processing oil.